segmentation fault when creating connect 4 board c program - c

Question

I'm creating a connect-4 game... I have a lot of it done; however, the way I was creating my board was static & it needed to be dynamic, so I've made a side program to fix this before implementing it in my main program. For some reason, the if & else-if conditionals in this chunk of code create a segmentation fault, and I can't figure out why...
// for the rows/columns of the board
for(row = num_rows - 1; row >= 0; row--){
printf("|");
for(col = 0; col < num_columns; col++){
if(aPtr[row][col] == '0') {
printf("| X ");
}
else if(aPtr[row][col] == '1') {
printf("| O ");
}
else {
printf("| ");
}
}
puts("||");
}
when I comment these conditionals out the board prints just fine & looks like this
------ Connect *Four ------
Connect X Command Line Game
&&===================&&
|| | | | | ||
|| | | | | ||
|| | | | | ||
|| | | | | ||
|| | | | | ||
|| | | | | ||
|| | | | | ||
|| | | | | ||
|| | | | | ||
|| | | | | ||
&&===================&&
1 2 3 4 5
the entirety of this side-program is below, any insight as to why this segmentation fault is occurring will be appreciated.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
void initialize(int num_rows, int num_cols, char **aPtr) {
int i, r, c;
// create the space for the board
aPtr = malloc(num_rows * sizeof(char*));
for (i = 0; i < num_rows; i++){
aPtr[i] = malloc(num_cols * sizeof (char));
}
// go through the board and set all values equal to -1
for (r = 0; r < num_rows; r++) {
for (c = 0; c < num_cols; c++) {
aPtr[r][c] = '9';
printf("%c", aPtr[r][c]);
}
printf("\n");
}
}
void printBoard(int num_rows, int num_columns, char **aPtr) {
int row, col;
printf("\n");
puts("------ Connect *Four ------");
puts("Connect X Command Line Game");
// for fancy top of board frame
printf("&&");
for(col = 1; col < num_columns; col++) {
printf("====");
}
printf("===");
printf("&&\n");
// for the rows/columns of the board
for(row = num_rows - 1; row >= 0; row--){
printf("|");
for(col = 0; col < num_columns; col++){
// if(aPtr[row][col] == '0') {
// printf("| X ");
// }
// else if(aPtr[row][col] == '1') {
// printf("| O ");
// }
// else {
printf("| ");
// }
}
puts("||");
}
// for fancy bottom of board frame
printf("&&");
for(col = 1; col < num_columns; col++) {
printf("====");
}
printf("===");
printf("&&\n");
printf(" ");
if (col < 100){
for(col = 0; col < num_columns; col++) {
if (col < 10) {
printf(" %d ", col + 1);
}
else {
printf("%d ", col + 1);
}
}
puts("\n");
}
}
// *******************************************************************************************************
// *******************************************************************************************************
int main (int argc, char *argv[]) {
char **aPtr;
int height = 10;
int width = 5;
int i;
initialize(height, width, aPtr);
printBoard(height, width, aPtr);
}

Answer 1

Here is the modification of your code, maybe it will help. Note that I'm passing &aPtr and *aPtr = (char*) malloc(...)
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
void initialize(int num_rows, int num_cols, char **aPtr) {
int i, r, c;
// create the space for the board
*aPtr = (char*) malloc(num_rows * sizeof(char*));
if(*aPtr == NULL)
{
free(*aPtr);
printf("Memory allocation failed");
}
for (i = 0; i < num_rows; i++){
aPtr[i] = (char *) malloc(num_cols * sizeof (char));
}
// go through the board and set all values equal to -1
for (r = 0; r < num_rows; r++) {
for (c = 0; c < num_cols; c++) {
aPtr[r][c] = '9';
printf("%c", aPtr[r][c]);
}
printf("\n");
}
}
void printBoard(int num_rows, int num_columns, char **aPtr) {
int row, col;
printf("\n");
puts("------ Connect *Four ------");
puts("Connect X Command Line Game");
// for fancy top of board frame
printf("&&");
for(col = 1; col < num_columns; col++) {
printf("====");
}
printf("===");
printf("&&\n");
// for the rows/columns of the board
for(row = num_rows - 1; row >= 0; row--){
printf("|");
for(col = 0; col < num_columns; col++){
if(aPtr[row][col] == '0') {
printf("| X ");
}
else if(aPtr[row][col] == '1') {
printf("| O ");
}
else {
printf("| ");
}
}
puts("||");
}
// for fancy bottom of board frame
printf("&&");
for(col = 1; col < num_columns; col++) {
printf("====");
}
printf("===");
printf("&&\n");
printf(" ");
if (col < 100){
for(col = 0; col < num_columns; col++) {
if (col < 10) {
printf(" %d ", col + 1);
}
else {
printf("%d ", col + 1);
}
}
puts("\n");
}
}
// *******************************************************************************************************
// *******************************************************************************************************
int main (int argc, char *argv[]) {
char *aPtr;
int height = 10;
int width = 5;
int i;
initialize(height, width, &aPtr);
printBoard(height, width, &aPtr);
}
Note that you are doing: aPtr[r][c] = '9'; so your board is empty, but if you change it to say 0you would get something like:
------ Connect *Four ------
Connect X Command Line Game
&&===================&&
|| X | X | X | X | X ||
|| X | X | X | X | X ||
|| X | X | X | X | X ||
|| X | X | X | X | X ||
|| X | X | X | X | X ||
|| X | X | X | X | X ||
|| X | X | X | X | X ||
|| X | X | X | X | X ||
|| X | X | X | X | X ||
|| X | X | X | X | X ||
&&===================&&
1 2 3 4 5
I'm assuming that's what you expected?